Enhancing the Fluorescence of Graphene Quantum Dots with a Oxidation Way

2014 ◽  
Vol 887-888 ◽  
pp. 156-160 ◽  
Author(s):  
Ting Han ◽  
Xue Jiao Zhou ◽  
Xiao Chen Wu
Keyword(s):  
Quantum Dots ◽  
Fenton Reaction ◽  
Graphene Quantum Dots ◽  
Quantum Yields ◽  
Photoluminescence Intensity ◽  
Oxidation Treatment ◽  
Fluorescence Quantum Yields ◽  
Bright Yellow ◽  
Simple Pathway ◽  
Green Fluorescent

It is a facile and efficient way to produce grapheme quantum dots (GQDs) through photo-Fenton reaction. However, the fluorescence of the as-generated GQDs is weak. Here, bright yellow-green fluorescent graphene quantum dots (GQDs) were prepared by post-oxidation of the GQDs with H2O2. The fluorescence quantum yields of the post-oxidized GQDs (O-GQDs) increased from 0.08% to 3.3% and the maximum emission wavelength shifted from 450 to 510 nm. The O-GQDs exhibit excitation-independent and pH-dependent photoluminescence behaviors. The increase of the photoluminescence intensity is attributed to the more carbonyl and carboxyl groups after the post-oxidation. The post-oxidation treatment offers a simple pathway to enhance the fluorescence of GQDs.

Synthesis, Photoluminescence and Bio-Targeting Applications of Blue Graphene Quantum Dots

2016 ◽  
Vol 16 (4) ◽  
pp. 3457-3467 ◽  
Author(s):  
Jigang Wang ◽  
Ji Zhou ◽  
Wenhua Zhou ◽  
Jilong Shi ◽  
Lun Ma ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Sodium Hydroxide ◽  
Heating Temperature ◽  
Thin Sheet ◽  
Graphene Quantum Dots ◽  
Photoluminescence Intensity ◽  
Cytotoxic Effects ◽  
Different Temperatures ◽  
Blue Photoluminescence

Chemical derived graphene oxide, an atomically thin sheet of graphite with two-dimensional construction, offers interesting physical, electronic, thermal, chemical, and mechanical properties that are currently being explored for advanced physics electronics, membranes, and composites. Herein, we study graphene quantum dots (GQD) with the blue photoluminescence under various parameters. The GQD samples were prepared at different temperatures, and the blue photoluminescence intensity of the solution improved radically as the heating temperatures increased. Concerning PL peak and intensity of the quantum dots, the results demonstrated dependence on time under heating, temperature of heating, and pH adjusted by the addition of sodium hydroxide. After hydrothermal synthesis routes, the functional groups of graphene oxide were altered the morphology showed the stacking configuration, and self-assembled structure of the graphene sheets with obvious wrinkles appeared at the edge structures. In addition, absorption, PL, and PLE spectra of the graphene quantum dots increase with different quantities of sodium hydroxide added. Finally, using GQD to target PNTIA cells was carried out successfully. High uptake efficiency and no cytotoxic effects indicate graphene quantum dots can be suitable for bio-targeting.

scholarly journals Separating graphene quantum dots by lateral size through gel column chromatography

RSC Advances ◽  
2019 ◽  
Vol 9 (33) ◽  
pp. 18898-18901 ◽  
Author(s):  
Wentian Wu ◽  
Jiamin Cao ◽  
Min Zhong ◽  
Haixia Wu ◽  
Fangwei Zhang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Column Chromatography ◽  
Fenton Reaction ◽  
Graphene Quantum Dots ◽  
Lateral Size

GQDs prepared through a photo-Fenton reaction were separated into eight groups with different sizes and fluorescent colors via gel column chromatography.

Effect of nitrogen doping on the photoluminescence intensity of graphene quantum dots

2017 ◽  
Vol 42 (18) ◽  
pp. 3642 ◽  
Author(s):  
Svette Reina Merden Santiago ◽  
Yee Ann Wong ◽  
Tzu-Neng Lin ◽  
Chiao-Hsin Chang ◽  
Chi-Tsu Yuan ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Nitrogen Doping ◽  
Graphene Quantum Dots ◽  
Photoluminescence Intensity

High-Quality Water-Soluble Core/Shell/Shell CdSe/CdS/ZnS Quantum Dots Balanced by Ionic and Nonionic Hydrophilic Capping Ligands

NANO ◽  
2016 ◽  
Vol 11 (07) ◽  
pp. 1650073 ◽  
Author(s):  
Lu Liu ◽  
Hu Xu ◽  
Bing Shen ◽  
Xinhua Zhong
Keyword(s):  
Quantum Dots ◽  
Colloidal Stability ◽  
Water Soluble ◽  
Quantum Yields ◽  
Surface Charges ◽  
Fluorescence Quantum Yields ◽  
Carboxylic Groups ◽  
Potential Applications ◽  
High Fluorescence ◽  
Capping Ligands

Pentaerythritol tetrakis 3-mercaptopropionate (PTMP) grafted poly(acryl acid) (PAA) ionic hydrophilic oligomer PAA-PTMP (PP) and dihydrolipoic acid (DHLA) grafted methoxypoly(ethylene glycol) (mPEG) nonionic hydrophilic oligomer mPEG-DHLA (PD) have been designed, synthesized and used as co-capping ligands in water-solubilization of hydrophobic quantum dots (QDs) via ligand exchange. The obtained oligomers with multi-thiol groups could bind strongly to the surface atoms of QDs. Meanwhile, the carboxyl groups (from PP) and mPEG segment (from PD) can render QDs water-soluble, and the free carboxylic groups can possibly be used for the further bioconjugation. The resulting water-soluble QDs have been characterized by ultraviolet-visible (UV-Vis), fluorescence, Fourier transform infrared (FTIR) spectroscopy as well as transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. The water-soluble QDs have relatively small hydrodynamic size (10[Formula: see text]12 nm), and importantly, retain high fluorescence quantum yields (up to 45%) compared with that of the originally hydrophobic QDs (49%). In addition, they have tunable surface charges and show excellent colloidal stability over a relatively broad pH range ([Formula: see text]), in high salt concentration, and even after thermal treatment at 100[Formula: see text]C. These results indicate that the water-soluble QDs coated by PP and PD oligomers have potential applications in cellular imaging and biosensor.

Stable CsPbBr3 perovskite quantum dots with high fluorescence quantum yields

2018 ◽  
Vol 42 (12) ◽  
pp. 9496-9500 ◽  
Author(s):  
Min Zhang ◽  
Zhi-Quan Tian ◽  
Dong-Liang Zhu ◽  
He He ◽  
San-Wei Guo ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Yields ◽  
Fluorescence Quantum Yields ◽  
Perovskite Quantum Dots ◽  
High Fluorescence ◽  
The Stability

After replacing oleylamine with (3-aminopropyl)triethoxysilane, the stability of the as-prepared CsPbBr3 QDs was significantly improved.

scholarly journals Rapid synthesis of graphene quantum dots using a continuous hydrothermal flow synthesis approach

RSC Advances ◽  
2017 ◽  
Vol 7 (24) ◽  
pp. 14716-14720 ◽  
Author(s):  
Suela Kellici ◽  
John Acord ◽  
Nicholas P. Power ◽  
David J. Morgan ◽  
Paolo Coppo ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Environmentally Benign ◽  
Rapid Synthesis ◽  
Flow Synthesis ◽  
Benign Synthesis ◽  
Low Cytotoxicity ◽  
Green Fluorescent ◽  
Synthesis Approach ◽  
Hydrothermal Flow

A rapid and environmentally benign synthesis of green fluorescent graphene quantum dots (GQD) with low cytotoxicity via Continuous Hydrothermal Flow Synthesis (CHFS) aided by calix[4]arene tetrasulfonic acid (SCX4) as a particle size limiting agent.

Facile One-Pot Conversion of Petroleum Asphaltene to High Quality Green Fluorescent Graphene Quantum Dots and Their Application in Cell Imaging

2016 ◽  
Vol 33 (9) ◽  
pp. 635-644 ◽  
Author(s):  
Pinhui Zhao ◽  
Menglong Yang ◽  
Weiyu Fan ◽  
Xiaojuan Wang ◽  
Fanlong Tang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Cell Imaging ◽  
Graphene Quantum Dots ◽  
High Quality ◽  
One Pot ◽  
Green Fluorescent

scholarly journals Tailoring fluorescence emissions, quantum yields, and white light emitting from nitrogen-doped graphene and carbon nitride quantum dots

Nanoscale ◽  
2019 ◽  
Vol 11 (35) ◽  
pp. 16553-16561 ◽  
Author(s):  
Siyong Gu ◽  
Chien-Te Hsieh ◽  
Yasser Ashraf Gandomi ◽  
Jianlin Li ◽  
Xing Xing Yue ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Carbon Nitride ◽  
Solid Phase ◽  
Graphene Quantum Dots ◽  
Quantum Yields ◽  
Light Emitting ◽  
Nitrogen Doped ◽  
Microwave Assisted ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

Highly fluorescent N-doped graphene quantum dots (NGQDs) and graphitic carbon nitride quantum dots (CNQDs, g-C3N4) were synthesized using a solid-phase microwave-assisted (SPMA) technique.

Near-infrared Ag2Se quantum dots with distinct absorption features and high fluorescence quantum yields

RSC Advances ◽  
2016 ◽  
Vol 6 (44) ◽  
pp. 38183-38186 ◽  
Author(s):  
Li-Juan Shi ◽  
Chun-Nan Zhu ◽  
He He ◽  
Dong-Liang Zhu ◽  
Zhi-Ling Zhang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Near Infrared ◽  
Quantum Yields ◽  
Extinction Coefficients ◽  
Fluorescence Quantum Yields ◽  
High Fluorescence ◽  
Absorption Features ◽  
Molar Extinction Coefficients

Near-infrared Ag2Se QDs with distinct absorption features ranging between 830–954 nm and fluorescence quantum yields up to 23.4% were controllably synthesized, and the molar extinction coefficients of the Ag2Se QDs were determined.

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